package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {
    @Resource
    private IUserService userService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private IFollowService followService;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            this.saveBlogWithUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result queryBlogById(Long id) {
        // 获取blog信息
        Blog blog = getById(id);
        // 判断是否获取成功
        if (blog == null) {
            return Result.fail("笔记不存在");
        }
        // 获取有关用户信息
        saveBlogWithUser(blog);
        // 查询blog是否已经被点赞---单职务
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    // 修改set数据类型->zset数据类型
    private void isBlogLiked(Blog blog) {
        // 获取登录用户
        UserDTO user = UserHolder.getUser();
        if (user == null) {
            // 用户未登录,无需查询是否点赞
            return;
        }
        // 判断当前登录用户是否已经点赞
        Long userId = user.getId();
        String key = BLOG_LIKED_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }

    private void saveBlogWithUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    // 修改set数据类型->zset数据类型,为了后续的点赞排行榜功能
    @Override
    public Result blogLiked(Long id) {
        // 获取当前用户id
        Long userId = UserHolder.getUser().getId();
        // 判断用户是否已经点赞过该笔记了---通过set集合判断
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) {
            // 如果没点赞过,则修改数据库liked字段+1,同时往集合里添加用户id
            boolean success = update().setSql("liked = liked + 1").eq("id", id).update();
            if (success) {
                // 存入当前时间戳作为score
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        } else {
            // 如果已经点赞过,则修改数据库liked字段-1,同时往集合里移除用户id
            boolean success = update().setSql("liked = liked - 1").eq("id", id).update();
            if (success) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        // 返回
        return Result.ok();
    }

    @Override
    public Result queryBlogLikes(Long id) {
        // 查询top5的点赞用户
        String key = BLOG_LIKED_KEY + id;
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (top5 == null || top5.isEmpty()) {
            return Result.ok(Collections.emptyList());
        }
        // 解析出其中的用户id
        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        // WHERE id IN (5,1) ORDER BY FIELD (id,5,1)
        // 强制指定id顺序
        String idStr = StrUtil.join(",", ids);
        // 根据这些id获取用户集合
        List<UserDTO> userDTOS = userService.query()
                .in("id", ids)
                .last("ORDER BY FIELD (id," + idStr + ")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        // 返回,注意数据类型应该是UserDTO
        return Result.ok(userDTOS);
    }

    @Override
    public Result saveBlog(Blog blog) {
        // 获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 保存探店博文
        boolean isSuccess = save(blog);
        if (!isSuccess) {
            return Result.fail("笔记保存失败");
        }
        // 保存成功
        // 查询笔记作者的所有粉丝 SELECT * FROM tb_follow WHERE follow_user_id = ?
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();
        for (Follow follow : follows) {
            // 获取每个粉丝的id
            Long id = follow.getUserId();
            String key = FEED_KEY + id;
            // 推送笔记id到每个粉丝的收件箱
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        }
        // 返回id
        return Result.ok(blog.getId());
    }

    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        // 1.获取本用户id
        Long userId = UserHolder.getUser().getId();
        // 2.获取代取的日记id和对应的score(时间戳)
        String key = FEED_KEY + userId;
        // 执行命令 ZREVRANGEBYSCORE key max min [withscores] [limit offset count]
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        // 非空判断
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        // 3.解析出其中的 blog_id(需要保存) , 最小时间戳 minTime , offset -- 这一步最关键
        // id集合需要指定长度,不然长度不一致处理的话会消耗额外性能
        List<Long> ids = new ArrayList<>(typedTuples.size());
        // 不是第一次的话偏移量offset最小从1开始
        int os = 1;
        long minTime = 0;
        for (ZSetOperations.TypedTuple<String> typedTuple : typedTuples) {
            // 获取笔记id
            ids.add(Long.valueOf(typedTuple.getValue()));
            // 获取score(该笔记对应的时间戳)
            long time = typedTuple.getScore().longValue();
            if (minTime == time) {
                os++;
            } else {
                // 还不是最小时间,需要重新设置
                minTime = time;
                // 只有分页查询到的最小时间有多个时,才需要更改offset
                os = 1;
            }
        }
        // 4.根据id集合查询blog集合 --- 注意这里会有使用in的风险问题
        // 强制指定id顺序
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query()
                .in("id", ids)
                .last("ORDER BY FIELD (id," + idStr + ")").list();
        for (Blog blog : blogs) {
            // 查询blog有关的用户
            this.saveBlogWithUser(blog);
            // 查询blog是否被点赞
            this.isBlogLiked(blog);
        }

        // 5.返回
        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);

        return Result.ok(r);
    }



}
